feat: known-good CPU audio + 1080p VAAPI + KMS display wall

Working snapshot before the OpenVINO MetricGAN GPU spike:
thread-capped SpeechBrain DelaySum+MetricGAN on CPU, hop 200 ms,
video hold for A/V sync, Arc VAAPI H.264, headless kmssink wall.
32 tests passing. Do not treat this as a GPU audio path.

scripts/dump_drm.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+"""Print a compact DRM connector/CRTC/plane map from drm_info -j."""
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+
+
+def main() -> int:
+    raw = subprocess.check_output(["drm_info", "-j"], text=True)
+    data = json.loads(raw)
+    for node, info in data.items():
+        driver = info.get("driver", {}).get("name") or info.get("driver_name")
+        device = info.get("device", {})
+        print(f"NODE {node} driver={driver} device={device}")
+        conns = info.get("connectors") or info.get("Connector") or []
+        if isinstance(conns, dict):
+            conns = list(conns.values())
+        crtcs = info.get("crtcs") or []
+        planes = info.get("planes") or []
+        print(f"  crtcs={len(crtcs)} planes={len(planes)} connectors={len(conns)}")
+        if conns and isinstance(conns[0], dict):
+            print("  connector keys:", sorted(conns[0].keys())[:20])
+        for c in conns:
+            if not isinstance(c, dict):
+                print("  conn", c)
+                continue
+            cid = c.get("id") or c.get("object_id")
+            typ = c.get("type") or c.get("connector_type")
+            name = c.get("name")
+            st = c.get("status")
+            modes = c.get("modes") or []
+            mode0 = None
+            if modes:
+                m = modes[0]
+                if isinstance(m, dict):
+                    mode0 = f"{m.get('name') or m.get('clock')} {m.get('hdisplay')}x{m.get('vdisplay')}"
+                else:
+                    mode0 = str(m)[:80]
+            print(f"  connector id={cid} type={typ} name={name} status={st} mode0={mode0}")
+        if planes and isinstance(planes[0], dict):
+            print("  plane keys:", sorted(planes[0].keys())[:20])
+            for p in planes[:8]:
+                print("   plane", {k: p.get(k) for k in list(p)[:12]})
+        if crtcs and isinstance(crtcs[0], dict):
+            print("  crtc keys:", sorted(crtcs[0].keys())[:20])
+            for cr in crtcs:
+                print("   crtc", {k: cr.get(k) for k in list(cr)[:12]})
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())

scripts/speaker_invite.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+"""Print a LiveKit Meet URL + token so a speaker can join and share a screen.
+
+STUB / future: do not use until the production LiveKit server is online.
+The third display currently shows a placeholder only.
+"""
+from __future__ import annotations
+
+import argparse
+import sys
+from pathlib import Path
+from urllib.parse import quote, urlparse
+
+ROOT = Path(__file__).resolve().parents[1]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+from config import load_config
+from tokens import make_speaker_token
+
+
+def public_url(cfg) -> str:
+    if cfg.livekit_public_url:
+        return cfg.livekit_public_url.rstrip("/")
+    parsed = urlparse(cfg.url)
+    host = parsed.hostname or "127.0.0.1"
+    if host in ("127.0.0.1", "localhost"):
+        host = "10.200.0.20"
+    scheme = parsed.scheme or "ws"
+    port = parsed.port
+    if port:
+        return f"{scheme}://{host}:{port}"
+    return f"{scheme}://{host}"
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser(description=__doc__)
+    ap.add_argument("--identity", default="", help="default: DISPLAY_SPEAKER_PARTICIPANT")
+    ap.add_argument("--name", default="Speaker")
+    args = ap.parse_args()
+    cfg = load_config()
+    identity = args.identity or cfg.display_speaker_participant or "speaker"
+    token = make_speaker_token(cfg.api_key, cfg.api_secret, cfg.room, identity, args.name)
+    url = public_url(cfg)
+    meet = (
+        "https://meet.livekit.io/custom"
+        f"?liveKitUrl={quote(url, safe='')}&token={quote(token, safe='')}"
+    )
+    print(f"room:     {cfg.room}")
+    print(f"identity: {identity}")
+    print(f"url:      {url}")
+    print(f"token:    {token}")
+    print()
+    print("Open this on the speaker laptop, then Share screen:")
+    print(meet)
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())